Pathology - ophtho

Question 1

Aqueous humor pathway

Answer 1

ciliary epithelium –> posterior chamber –> sphincter –> anterior chamber –> trabecular meshwork –> Canal of Schlemm

Question 2

Glaucoma drugs

Answer 2

decr. aq humor synth: epinephrine, brimonidine, timolol, acetazolomide
incr. aq humor outflow: pilocarpine (opening of trabecular meshwork), physostigmine (both are cholinomimetics)

Question 3

Eye too short for refractive power of cornea and lens

Answer 3

Hyperopia (light focused behind retina)

Question 4

Eye too long for refractive power of cornea and lens

Answer 4

Myopia (light focused in front of retina)

Question 5

Impaired accommodation due to loss of elasticity

Answer 5

Presbyopia

Question 6

Painless bilateral opacification of the eye

Answer 6

Cataract

Can be caused by steroids, sunlight, galactose excess, DM, infection

Question 7

Optic disc atrophy with cupping

Answer 7

Glaucoma

usually seen with incr. IOP

Question 8

Open vs. closed angle glaucoma

Answer 8

Open angle - blocked trabecular meshwork

Closed angle - obstruction of aq humor flow by lens pushing on the iris (which blocks flow through trabecular meshwork)

Question 9

Vision changes in macular degeneration

Answer 9

distortion and loss of central vision (scotoma!)

dry = deposition of yellowish material in and beneath Bruch membrane and RPE –> drusen

wet = rapid loss of vision due to bleeding secondary to choroidal neovascularization, treat with anti-VEGF or laser

Question 10

Non-proliferative vs. proliferative diabetic retinopathy

Answer 10

NP: damaged capillaries leak blood, causing hemorrhages and macular edema

P: chronic hypoxia causes neovascularization –> traction on retina

Question 11

Layers in retinal detachment

Answer 11

Separation of neurosensory layer from the pigmented epithelium

Question 12

Progression of retinitis pigmentosa

Answer 12

Starts with night blindness (loss of rods first!)

Look for bone spicule-shaped deposits around macula

Question 13

Miosis vs. Mydriasis

Answer 13

Constriction (parasympathetic, 2 neurons, short ciliary nerve) vs. dilation (sympathetic, 3 neurons, long ciliary nerve)

Question 14

Ptosis + down and out gaze + blown pupil

Answer 14

3rd nerve palsy

Motor output affected by vascular disease (is on inside of CN3, whereas vasculature runs on the periphery)

Parasympathetic output affected first by compression (PCOMM aneurysm, uncal herniation)

Question 15

Head tilt + eye moving upward with contralateral gaze

Answer 15

4th nerve palsy

Look for problems going down stairs

Question 16

Medially directed eye that can’t abduct

Answer 16

6th nerve palsy

Question 17

Meyer loop vs. dorsal optic radiation

Answer 17

Meyer loop = inferior retina, loops around inferior horn of lateral ventricle

Dorsal optic radiation = superior retina, takes shortest path via internal capsule

Question 18

Impaired adduction

Answer 18

Sign of internuclear ophthalmoplegia

MLF lesion = lack of visual coordination in horizontal field (lack of contralateral CN3 firing), nystagmus opposite to lesion

Left INO = left eye is paralyzed